Call Handoff Between Different Networks

ABSTRACT

Disclosed are techniques for hosting a communication session in a call server between communication devices. The call server functions as a bridge service between the communication devices joining an original communication link between the first communication device and the call server with a second communication link between the second communication device and the call server. The first communication device includes at least two RF transceivers each capable of communicating with the call server over a separate network. The call server receives a signal from the first communication device indicative of the need to handoff the original communication link to an alternate communication link on an alternate network. The call server establishes the alternate communication link with the first communication device on the alternate network and joins it with the second communication link to maintain the communication session between the communication devices.

BACKGROUND

Mobile telephony devices utilizing wireless communication protocols areubiquitous. Many of these devices utilize one of the competing cellularnetworks (e.g., GSM or CDMA) to place and receive telephone calls toother telephony endpoint devices. A telephony endpoint device mayinclude another mobile telephony device on the same or another cellularnetwork, a Voice-over-IP (VoIP) telephony device, and/or a plain oldtelephone service (POTS) telephony device. Each of these telephonyendpoint devices may use a different access network but all areinterfaced at some point to allow for communication among the differentnetworks.

Recently, there has been introduced another type of mobile telephonydevice, one that is capable of utilizing multiple different networksdepending on the current location or network conditions pertaining tothe mobile telephony device. Such a mobile telephony device may becharacterized as a hybrid mobile device due to its capability of makingand receiving telephone calls on at least two distinct networks. Somehybrid mobile devices include the ability to start or establish atelephone call on one network (e.g., an IP based VoIP network over aWiFi connection) and handoff the call to a second network (e.g., acellular network) when conditions on the original network degrade. Sucha handoff may occur, for instance, when the mobile hybrid device movesout of range of the IP based WiFi access point. Rather than dropping thecall, the hybrid mobile device, in conjunction with the a network basedserver, may switch to a cellular connection prior to severing the WiFiVoIP connection thereby ensuring that the hybrid mobile device staysconnected to the other telephony endpoint and the call is not dropped.

Described herein are methods, systems, and techniques for implementingsuch an inter-network handoff for a hybrid mobile.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary networked environment for implementingcertain exemplary embodiments described herein.

FIG. 2 is a block diagram illustrating some of the functions of the callserver according to one or more embodiments described herein.

FIG. 3 is a block diagram illustrating a hybrid mobile device accordingto one or more embodiments described herein.

FIG. 4 is a block diagram illustrating establishing a communicationsession between communication devices according to one or moreembodiments described herein.

FIG. 5 is a block diagram illustrating a communication session handoffbetween a hybrid mobile device and a call server utilizing differentnetworks according to one or more embodiments described herein.

FIG. 6 is an illustration of a logic flow diagram for executing ahandoff of a portion of a communication session between differentnetworks.

FIG. 7A is one embodiment of a messaging diagram for executing a handoffof a portion of a communication session between different networks.

FIG. 7B is another embodiment of a messaging diagram for executing ahandoff of a portion of a communication session between differentnetworks.

DETAILED DESCRIPTION

The embodiments described herein disclose systems and methods forintelligently structuring, handling, and enhancing communicationsessions between or among communication devices. The systems and methodsof the invention may be embodied in and performed by communicationdevices, call servers and other devices, and software instructionsexecuted by some or all of such devices, as will be explained in detailbelow. The different types of networks contemplated herein include, forexample, cellular mobile networks, the public switched telephone network(PSTN), and data networks, such as the Internet or other IP-basednetworks, including wide area networks, local area networks, andcombinations thereof.

As used herein the term “communications session” is meant to generallyindicate any one-way or two-way exchange of information between two ormore communication devices. Communication sessions may include voice,data, video, and multimedia communication sessions, or any other type ofdata communication sessions or messaging exchanges. As used herein, theterm “communication link” is intended to mean a physical or logicalchannel that connects two or more devices. A communication link may be asignaling link or a media link. In this context, a communication sessionmay be established via one or more communication links. One or moremedia streams may be transmitted over a communication link. A callserver may be situated between communication devices thereby making thecall server an endpoint in a communication link. The call server may behosted within an IP network such as, for instance, the Internet or aLAN/WAN accessible to the Internet.

The convergence of and inter-operation among different types of networktechnologies (e.g., heterogeneous network inter-operability) blurs theline between various distinct networks. This disclosure discusses accessnetworks that may be characterized as the portion of a communicationsnetwork that connects subscriber communication devices to a serviceprovider's core network. An access network may also be referred to asthe interface between the communication device and the network. Anothertype of interface may be the interface between networks. That is, theinterface necessary to facilitate seamless communications from onenetwork to another.

Therefore, references herein to a communication device capable ofconnecting to or communicating via a mobile carrier network refer to acommunication device equipped with a cellular transceiver for wirelesscommunication with basestations and other mobile carrier network accesspoints. Similarly, references herein to a communication device capableof connecting to or communicating via a data network refer to acommunication device equipped with a transceiver or other networkinterface for wireless communication (e.g., 802.11) with a router orother data network access point. One particular communication device maybe characterized herein as a wireless handset. A wireless handset mayinclude multiple RF transceivers, one of which may be operable toconnect to an access network for a mobile carrier network (e.g.,cellular network) and another of which may be operable to connect to anaccess network for an IP data network (e.g., 802.11).

FIG. 1 illustrates an exemplary networked environment 100 forimplementing certain exemplary embodiments described herein. Thenetworked environment 100 may include multiple distinct inter-connectednetworks such as, for instance, a large scale internet protocol (IP)network (e.g., the Internet) 101, one or more IP based local areanetworks or wide area networks (LAN/WAN) 122, mobile carrier networks110, and the PSTN 108. While these distinct networks utilize differentprotocols and signaling schemes, there are various interfaces that allowfor the seamless transition of voice and data (including text, audio,and video) such that various communication endpoints may communicatewith one another over one or more of these inter-connected networks.

The PSTN 108 can be characterized as a circuit switched point-to-pointcommunications network in which a physical connection between theendpoints is maintained for the duration of the connection. The PSTN 108may also be referred to as the legacy telephone network as it is thebackbone infrastructure for connecting endpoints comprised of Plain OldTelephone Service (POTS) phones 116.

Mobile carrier networks 110 (sometimes referred to as cellular networks)may come in different varieties based on the radio transmission scheme125 between a communication device known as a wireless handset (e.g.,mobile or cellular phone) 114 and the mobile carrier network basestation112 that is in communication with the wireless handset 114. Two suchradio transmission schemes are the Global System for MobileCommunications (GSM) and Code Division Multiple Access (CDMA). Theseradio transmission schemes are incompatible with one anothernecessitating an intervening interface to allow communication betweenendpoints on either network. In addition, each network may operate overa specific frequency ranges. Often, there may even be an interveningnetwork such as the PSTN 108 between two distinct mobile carriernetworks 110. Each mobile carrier network 110 includes an interface tothe PSTN 108 such that calls crossing that interface can be handled bythe receiving network whether it is a mobile carrier network 110 or thePSTN 108.

Various mobile carrier network operators base their network on one ofthe radio transmission schemes 125 and provide service to wirelesshandsets 114 using that radio transmission scheme 125 over a definedfrequency band. For example, a wireless handset 114 wirelesslycommunicates with a basestation 112 that serves as an access network tothe mobile carrier network 110. The basestation 112 authenticates andauthorizes the wireless handset 114 to the mobile carrier network 110and, in conjunction with other equipment within the mobile carriernetwork 110, manages calls to and from the wireless handset 114. Themobile carrier network 110 provides connectivity for any wirelesshandsets 114 capable of cellular transmission that are physicallylocated within range of the mobile carrier network 110. The range of amobile carrier network 110 depends in part on an amplification, power,and/or energy associated with the antennas comprising cellular basestation, wireless handsets 114 and the like. As the wireless handset 114moves toward the outer range of the mobile carrier network 110, thestrength of the cellular signals degrade.

Similarly, an IP based data network 122, 101 may provide wirelessconnectivity to wireless handsets 114 within range of an IP access point120. For instance, an IP access point 120 may provide wirelessconnectivity using any of the 802.11 WiFi standards, WiMAX standards,and/or any other type of IP based connectivity standard. As will beappreciated by those of skill in the art, a wireless handset 114 mayexperience a stronger connection signal when located closer to an IPaccess point 120 than when located further away from the IP access point120. Thus, the strength of the wireless data connection may fade as thewireless handset 114 moves away from an IP access point 120.

There may also be one or more alternative networks 115 that may provideaccess to the Internet 101 for a hybrid mobile device 124 or otherwireless handset devices 114. One such alternative network 115 may becharacterized as a WiMax network operable over the 802.16 wirelessprotocol standard. Another such alternative network 115 may becharacterized as a whitespace network. A whitespace network may utilizeRF spectrum that is shared with television broadcasters. The televisionbroadcasters do not necessarily need to utilize all the spectrumallocated to them to broadcast their video signals. The unused spectrummay be tapped into to provide an alternative RF access point to analternative network 115 that can interface with the Internet 101.

The collection of IP based data networks illustrated in FIG. 1 such asLAN/WANs 122, and the Internet 101 all run on a packet based datatransfer protocol characterized as packet switching. Packet switchingessentially chops up a data stream (e.g., text, voice, data) intosegments and transfers them across an IP network to a destination wherethe packets are re-assembled into the original data stream for output.Voice over IP (VoIP) is a specialized subset of IP packet basedcommunication directed to IP telephony. End user devices 118 utilize anIP access point 120 to the larger IP network. The IP access point 120may be wired, wireless (e.g., WiFi), or a combination wired/wirelessaccess point such as those illustrated in FIG. 1. A VoIP communicationdevice 118 may communicate with an IP access point 120 to gain access tothe larger IP network 101 and other communication devices. The VoIPcommunication device 118 has been illustrated as a wireline type devicebut may just as easily be a wireless device communicable with the IPaccess point 120 over, for instance, one or more of the 802.11protocols.

In certain embodiments, mobile carrier network(s) 110 include cellularnetworks or portions of cellular networks based on GSM, LTE, CDMA,and/or any other cellular network standards. IP based data networks 122,101 include, for example, the Internet, one or more intranets, wide areanetworks (WANs), local area networks (LANs), and the like, portions orall of which may be wireless and/or wired. For instance, an IP baseddata network 122, 101 may be a wireless network or a portion of awireless network implemented using an IEEE 802.11 standard, WiMAX,and/or any other wireless data communication standard. As is known inthe art, the resources the various networks 108 (PSTN), 110 (MobileCarrier), 122, 101 (IP Based) may interface with the call server 102through gateway devices, routers and/or other appropriate devices (notshown). Similarly, the wireless handsets 114 may interface with thevarious networks 108 (PSTN), 110 (Mobile Carrier), 122, 101 (IP based)and alternative networks 115 through appropriate access points 111, 120(some not shown).

As one may surmise, it is far less complicated when both communicationdevices in a communications system utilize the exact same network. Forinstance, POTS phone to POTS phone would communicate over the PSTN onlywhile a GSM wireless handset to another GSM wireless handset of the samemobile service provider may be handled within the mobile carriernetwork. Lastly, a VoIP phone calling another VoIP phone would stayexclusively on a packet based series of networks like LAN/WANs, 122and/or the Internet 101.

Things get more complicated when the communication devices areassociated with different networks. For instance, a POTS phone placing acall to a wireless handset or a VoIP phone calling a POTS phone. Inthese scenarios, and others, there is an interface between the networksthat serves to resolve any differences so that a communication sessionmay be connected and maintained. As described above there may be anintervening network between two endpoint networks. For instance, eachmobile carrier network 110 includes an interface to the PSTN 108 suchthat calls crossing that interface can be handled by the receivingnetwork whether it is a mobile carrier network 110 or the PSTN 108.Similarly, each VoIP service provider on an IP packet based network 122,101 includes an interface to the PSTN 108 such that calls crossing thatinterface can be handled by the receiving network whether it is an IPpacket based network 122, 101 or the PSTN 108. Thus, the PSTN 108 servesas a common routing network for endpoint communication devices that areassociated with other networks. It is possible to create a VoIPinterface such that IP packet based networks 122, 101 can interfacedirectly with mobile carrier networks 110.

There is one aspect that each network (e.g, PSTN 108, VoIP 101, 122 andmobile carrier 110) has in common that facilitates communicationsessions among communication devices native to the various networks. Thecommonality is that each communication device has a unique telephonenumber (TN) as an identifier. The format of the telephone number isidentical regardless of the network in use. In North America, forinstance, the TN is a ten-digit number. Each communication device inNorth America is associated with a 10 digit telephone number thatsubscribers ‘dial’ to reach other subscribers no matter the network theother subscriber uses. Thus, users of communication devices need notworry about how to reach another user because all communication deviceskey off an associated telephone number. From the user's perspective, itis up to the networks to resolve any connection issues and allow callsto be connected so that a communication session may occur. For the mostpart, these network differences have been resolved on an industry widescale and it is relatively routine to place and connect calls betweenendpoints regardless of their native networks.

Each network service provider may provide equipment (communicationdevices) and service plans to its subscribers. These service plans canvary greatly in cost depending on the expected use of network resources.In addition, some service plans may bundle data and voice services inthe cost of the service plan. This is often the case for mobile carriernetwork 110 subscribers since the ability to access data networks suchas the Internet on a mobile device is a desired service. This isespecially the case when a WiFi data connection is out of range. As aresult, bundled voice and data services can place a significant burdenon the mobile carrier network resources that can lead to userestrictions for bundled voice/data plans.

One approach that addresses the mobile network congestion problem is acommunication device that may be characterized as a hybrid mobile device124. The hybrid mobile device 124 may be associated with networkinfrastructure that defaults telephony services to a WiFi connection 123using, for instance, VoIP over an 802.11 protocol via an IP access point120. The hybrid mobile device 124 may default to WiFi mode whenavailable and may only switch to a mobile carrier network 110 connectionvia a radio transmission scheme 125 to a basestation 112 (cellular mode)when the WiFi connection 123 is lost or unavailable. As it pertains todata, this heterogeneous network switching may be referred to as WiFioffloading. For telephony services, however, such a soft handoverbetween heterogeneous networks is a more daunting and complex process.

One implementation of a soft handover of a voice call betweenheterogeneous networks involves associating two telephone numbers to ahybrid mobile device 124. A first telephone number may be characterizedas a ‘data’ telephone number that is based on a VoIP telephony scheme.The second number may be characterized as a ‘mobile’ telephone numberthat is used in conjunction with a radio transmission scheme 125associated with a mobile carrier network 110. The subscriber may only beaware of the data number and not have actual knowledge of the mobilenumber. For all intents and purposes, the subscriber places and receivescalls using the data telephone number. To reach the subscriber, a secondcommunication device would dial the subscriber's data telephone number.

When the hybrid mobile device 124 is connected with an IP access point120, telephony services and functions are handled using VoIP. To dialout, the subscriber dials the telephone number of the intendedrecipient's communication device. The intelligence within the hybridmobile device 124 recognizes that the subscriber is attempting to placea call and notes the telephone number entered. In actuality, the hybridmobile device 124 connects with a call server 102 hosted in an IP basednetwork 101 such as the Internet. The call server 102 may have a pool oftelephone numbers reserved for establishing connections with the hybridmobile device 124. The hybrid mobile device 124 while appearing to dialthe intended telephone number actually dials one of the pool numbersassociated with the call server 102 and establishes a firstcommunications link. The call server 102 then determines the intendedtelephone number that was dialed by the subscriber and places a call tothe communication device associated with that telephone number (calledcommunication device). Upon connecting the second communication linkbetween the call server and the called communication device, the callserver 102 joins the first communication link with the secondcommunication link to create a full-duplex communications sessionbetween the hybrid mobile device 124 and the called communicationdevice.

The communication session will stay active until one of the respectivecommunication devices terminates the call. Sometimes, however, thehybrid mobile device 124 may experience a loss of service with ordegradation to the WiFi connection. This commonly occurs if the hybridmobile device 124 moves out of range of the IP access point 120. In sucha scenario, it is necessary to hand the call over to the mobile carriernetwork 110 to avoid terminating the communication session. This may beaccomplished by creating a third communication link between the callserver 102 and the hybrid mobile device 124. The third communicationlink, however, may be routed through the mobile carrier network 110 tothe hybrid mobile device 124. When the first communication link is lostor is significantly degraded, it may be seamlessly replaced by the thirdcommunication link such that the call server 102 bridges or connects thethird communication link with the second communication link to maintainthe communication session.

On inbound calls to the hybrid mobile device 124, a callingcommunication device dials the data number of the hybrid mobile device124. This initiates a connection to the call server 102 as the datanumber is automatically routed to the call server 102. The call serverthen establishes a first communication link with the callingcommunication device. The call server 102 then establishes a secondcommunication link with the hybrid mobile device 124. The call serverdefaults to WiFi mode in attempting to establish the communication linkwith the hybrid mobile device 124. If the hybrid mobile device 124 isnot currently connected to an IP access point 120 and is thereforeinaccessible via VoIP over WiFi, the call server will switch to cellularmode. In cellular mode, the call server will establish the secondcommunication link over the mobile carrier network 110. This cannot bedone, however, using the hybrid mobile device's 124 data number sincethat number is unknown to the mobile carrier network 110. To establishthe second communication link between the call server 102 and the hybridmobile device 124, the call server accesses a translation table within adatabase that includes data/mobile number pairs in which each pair maybe associated with a hybrid mobile device 124. In this case, the callserver will lookup the data number and have a mobile number returned.The call server 102 may then establish the second communication link bydialing the mobile number and establishing a connection to the hybridmobile device 124. The call server may then join the first and secondcommunication links to create the full-duplex communication sessionbetween the calling device and the hybrid mobile device 124.

The communication session will stay active until one of the respectivecommunication devices terminates the call. While the communicationsession is in progress, the hybrid mobile device 124 may re-establish aWiFi connection. In such a scenario, it is desirable to hand the callover to the VoIP network to reduce the burden on the mobile carriernetwork 110. This may be accomplished by creating a third communicationlink between the call server 102 and the hybrid mobile device 124. Thistime the third communication link may be routed over the VoIP network101, 122 via an IP access point 120 to the hybrid mobile device 124.When the third communication link is sufficiently established, it mayseamlessly replace the first communication link such that the callserver 102 bridges or connects the third communication link with thesecond communication link to maintain the communication session.

In another outbound calling scenario, the hybrid mobile device 124 maynot have an initial connection via WiFi to a packet based VoIP network122, 101. An outbound call to a destination telephone number must beestablished over the mobile carrier network 110 using the mobile numberassociated with the hybrid mobile device 124. For caller ID purposes,however, the calling number is the data number associated with thehybrid mobile device 124. The call is again routed to and through thecall server 102. The first communication link is between the hybridmobile device 124 and the call server. This is accomplished by havingthe hybrid mobile device 124 automatically place a call to the callserver 102 using one of the pool of telephone numbers associated withthe call server. Just prior to the call, the hybrid mobile device 124may utilize the mobile carrier network's data services to send a messageto the call server 102. The message to the call server 102 may containthe mobile and data numbers of the hybrid mobile device 124 and thedestination telephone number such that when the call server 102 receivesthe call from the hybrid mobile device 124 using the mobile number, itcan place a call to the destination telephone number and substitute thedata telephone number in the caller ID field. Upon establishing thesecond communication link, the call server 102 may then join the firstand second communication links to create the full-duplex communicationsession between the hybrid mobile device 124 and the destination device.

FIG. 2 is a block diagram illustrating some of the functions of the callserver according to one or more embodiments described herein. The callserver 102 may comprise, for example, a server computer or any othersystem having computing capability. The schematic block diagram showsthat the call server 102 may include at least one processor 103, atleast one communication interface 109 (e.g., a network interface card orthe like), and a data storage component 105, each of which is coupled toa local interface 113. The local interface 113 may comprise, forexample, a data bus with an accompanying address/control bus or otherbus structure as can be appreciated. Stored in the data storagecomponent 105 are a memory 107 and multiple components 102 a-102 c(e.g., software applications) that are executable by the processor 103and that provide at least some of the functionality of the call server102.

Alternatively, a plurality of call servers 102 may be employed and maybe arranged, for example, in one or more server banks or computer banksor other arrangements. For example, a plurality of call servers 102together may comprise a cloud computing resource, a grid computingresource, and/or any other aggregated or distributed computingarrangement. Such call servers 102 may be located in a singleinstallation or may be distributed among different geographicallocations. For purposes of convenience, the call server 102 isillustrated in FIGS. 1 and 2 and referred to herein in the singular.Even though the call server 102 is referred to in the singular, it isunderstood that a plurality of call servers 102 may be employed invarious arrangements as described above.

The communication interface(s) 109 may include a voice-over-IP (VoIP)interface 106 adapted to exchange IP based audio data with other IPnetwork devices using a VoIP protocol. Another communication interface109 may be a PSTN interface 104 adapted to convert incoming PSTN audiodata to VoIP audio data and convert outgoing VoIP audio data to PSTNaudio data. Still another communication interface 109 may be an IP datainterface 117 adapted to exchange IP data with other IP network devices.This may include IP data exchanged with a mobile wireless handset 114,124 over an intermediate mobile carrier network 110. Yet anothercommunication network interface 109 may be directed toward analternative network 115 adapted to exchange data with a wireless handset114 or a hybrid mobile device 124. Examples of alternative network(s)115 may include, but are not limited to, WiMax and whitespace. Awhitespace network may be characterized as one that utilizes frequencyspectrum that is overlapping with that of broadcast television frequencyspectrum.

The call server 102 may further include several inter-operable softwaremodules operable with application programming interfaces (APIs) 121 andcommunication interfaces 109 and configured to intelligently manage thecommunication session. These software modules may include abridge/routing module 102 a, an intelligence module 102 b, and a handoffmodule 102 c. The aforementioned software modules have functional namesfor convenience and ease of reference. These functional names should notbe construed as limiting to the various software modules individually orthe call server 102 as a whole. There may be functions performed by oneor more of the software modules in conjunction with the APIs 121 andnetwork communication interfaces 109 that achieve a stated purpose orgoal.

The bridge/routing module 102 a may be configured to physically orlogically connect communication links. The intelligence module 102 b maybe configured to monitor network conditions and receive communicationsession data from the hybrid mobile device 124 regarding its connectionwith the IP access point 120 so as to intelligently determine the needfor a soft handoff to the mobile carrier network 110. Communicationsession data may refer to any data relating to a communication sessionor its constituent communication link(s), such as, but not limited to,detected signal strengths, available networks, protocol and bufferstatistics and analysis, environmental and/or geographical factors, theperformance of access points and other network components, pastinteractions between or among communication devices, access points andother network components, context of conversations during voice calls,and other data points described herein. The call handoff module 102 cmay be configured to initiate a handoff from one communication link toanother communication link with the assistance of the bridge/routingmodule 102 a and the intelligence module 102 b.

More specifically, the bridge/routing module 102 a may cooperate withthe APIs and network interfaces to physically or logically connectcommunication links to initially establish a communication sessionbetween communication devices and/or to perform a handoff of at leastone communication link of a communication session from one network toanother network. A communication session may be, for instance, between ahybrid mobile device 124 and a second telephony endpoint (e.g., 114,116, 118). The handoff may be caused by an instruction or commandreceived from the call handoff module 102 c. The bridge/routing module102 a may be configured to physically or logically establishcommunication links, join communication links, and sever communicationlinks to a common or shared communication session based on commands orinstructions received from the call server 102.

The intelligence module 102 b may cooperate with the APIs and networkinterfaces to monitor and gather (receive) data pertaining to networkconditions and communication device connections with various networks.The data may then be intelligently processed to predict or determine theneed for a handoff of at least one communication link of a communicationsession. The data received by the intelligence module 102 b may includeout of band and/or out of network signaling from a communication deviceto indicate that a handoff is needed. In such a case, the intelligencemodule 102 b may instruct the call server 102 to establish a newcommunication link via the bridge/routing module 102 a and then instructthe call handoff module 102 c to initiate a handoff process once the newcommunication link has been established.

The call handoff module 102 c may cooperate with the APIs and networkinterfaces to effect a handoff of a first communication link between thecall server 102 and the hybrid mobile device 124 to a secondcommunication link between the call server 102 and the hybrid mobiledevice 124. The call handoff module 102 c may receive data andinstructions from the intelligence module 102 b that indicates a handoffmay be needed imminently based on the degrading network conditionsassociated with the first communication link. The call handoff module102 c may then execute certain instructions to establish a secondcommunication link between the call server 102 and the hybrid mobiledevice 124. Once the second communication link has been established, thecall handoff module 102 c may instruct the bridge/routing module 102 ato join the second communication link to the communication session withthe other telephony device (114, 116, 118) prior to severing the firstcommunication link between the call server 102 and the hybrid mobiledevice 124.

The call server 102 may execute various applications and/or otherfunctionality for, among other things, setting-up, managing andtearing-down communication sessions between communication devices 124and 114, 116, 118. Also, various data may be stored in a data storage105 via memory 107 of the call server 102. Data storage 105 illustratedin FIG. 2 may be representative of a plurality of data stores, as can beappreciated. The data stored in the data storage 105, for example, maybe associated with the operation of the various applications and/orfunctional entities of the call server 102.

FIG. 3 is a block diagram illustrating a hybrid mobile device 124according to one or more embodiments described herein. The hybrid mobiledevice 124 may include a processor or processors 305 for controlling thevarious components and functions of the hybrid mobile device 124. Thehybrid mobile device 124 may also include multiple RF transceivers suchas, for instance, a WiFi transceiver 310, a cellular transceiver 315,and an alternate transceiver 320.

The WiFi transceiver 310 may be operable to communicate with an IPnetwork access point 120 using one or more of the 802.11 wirelesstransmission protocols. Upon connection with an IP network access point120, the hybrid mobile device 124 may exchange IP data with servers orother computers that are connected with or communicable with theInternet 101 via LAN/WAN 122. This may include the call server 102 shownin FIG. 1.

The cellular transceiver 315 may be operable to communicate with amobile carrier network 110 for both voice and IP data communications. Onthe voice side, the mobile carrier network 110 may be based on GSM,CDMA, or other communications protocols while on the IP data side, themobile carrier network 110 may be based on, for example, GPRS, EDGE,EV-DO, HSPA-D, HSPA-U, LTE, UMTS-WCDMA, UMTS-TDD, etc.

In one embodiment, the alternate transceiver 320 may be a WiMaxtransceiver that is operable to communicate with an IP network accesspoint using one or more of the 802.16 wireless transmission protocols.Upon connection with a WiMax network access point, the hybrid mobiledevice 124 may exchange IP data with servers or other computers that areconnected with or communicable with the Internet 101 via WiMax network115. This may include call server 102 shown in FIG. 1. In anotherembodiment, the alternate transceiver 320 may be a whitespacetransceiver that is operable to communicate with a whitespace networkaccess point. The whitespace network, in turn, may be communicable withthe Internet 101 to allow IP data communications between the hybridmobile device 124 and servers or other computers that are connected withor communicable with the Internet 115. This may include call server 102shown in FIG. 1.

The hybrid mobile device 124 may further include data storage 325,software applications 330, and various user interface(s) 335. The datastorage 325 may include, for example, one or more types of memorydevices including, but not limited to, flash memory usable for ROM, RAM,PROM, EEPROM, and cache. The software applications 330 may include, forexample, one or more software applications executable on or by theprocessor(s) 305 including, but not limited to, web browsers, emailapplications, application specific data and/or audio/video applications,call handoff applications, etc. The user interface(s) 335 may include,for example, a display, a touchscreen for soft-key input, speaker(s),microphone(s), a keyboard for hard-key input, and one or more buttons.

FIG. 4 is a block diagram illustrating establishing a communicationsession between communication devices 124, 410 according to one or moreembodiments described herein. In this implementation, the hybrid mobiledevice 124 may have two telephone numbers associated therewith. A firsttelephone number may be characterized as a ‘data’ telephone number thatis based on a VoIP telephony scheme implemented on an IP network suchas, for instance, LAN/WAN IP network 122 communicable with Internet 101.The second number may be characterized as a ‘mobile’ telephone numberthat is used in conjunction with a radio transmission scheme 125associated with a mobile carrier network 110. The user may only be awareof the data number and not have actual knowledge of the mobile number.For all intents and purposes, the user places and receives calls usingthe data telephone number. To reach the user, a second communicationdevice would dial the user's data telephone number.

When the hybrid mobile device 124 is connected with an IP access point120 to IP network 122, telephony services and functions are handledusing VoIP. To place a call, the user dials the telephone number of theintended recipient's communication device 410 using a dialer applicationthat may be one of the software applications 330. The intelligencewithin the hybrid mobile device 124 recognizes that the user isattempting to place a call and notes the telephone number entered. Inactuality, the hybrid mobile device 124 connects with the call server102 hosted in an IP based network 101 such as the Internet. The callserver 102 may have a pool of telephone numbers reserved forestablishing connections with the hybrid mobile device 124. The hybridmobile device 124 while appearing to dial the intended telephone numberactually dials one of the pool numbers associated with the call server102 and establishes a first communications link. This may occur over asignaling channel associated with the network that is establishedbetween the hybrid mobile device 124 and the call server 102. The callserver 102 then determines the intended telephone number that was dialedby the subscriber and places a call to the communication deviceassociated with that telephone number (called communication device).Upon connecting the second communication link between the call server102 and the called communication device 410, the call server 102 joinsthe first communication link with the second communication link tocreate a full-duplex communications session (e.g., media channelconnection) between the hybrid mobile device 124 and the calledcommunication device 410.

When the hybrid mobile device 124 is not connected with an IP accesspoint 120, telephony services and functions are defaulted over to themobile carrier network 110. To place a call, the user dials thetelephone number of the intended recipient's communication device 410.The intelligence within the hybrid mobile device 124 recognizes that theuser is attempting to place a call and notes the telephone numberentered. In actuality, the hybrid mobile device 124 connects with thecall server 102 hosted in an IP based network 101 such as the Internetby way of the mobile carrier network 110. The call server 102 may have apool of telephone numbers reserved for establishing connections with thehybrid mobile device 124. The hybrid mobile device 124 while appearingto dial the intended telephone number actually dials one of the poolnumbers associated with the call server 102. The mobile carrier network110 then routes the call to the call server 102. The call server 102establishes a first communications link with the hybrid mobile device124 that spans the IP network 101 and the mobile carrier network 110. Anintermediate network such as the PSTN 108 may be used to interfacebetween the IP network 101 and the mobile carrier network 110. This mayoccur over a signaling channel associated with the network that isestablished between the hybrid mobile device 124 and the call server102. The call server 102 then determines the intended telephone numberthat was dialed by the subscriber and places a call to the communicationdevice 410 associated with that telephone number (called communicationdevice). In addition, the call server substitutes the user's datatelephone number into the caller ID field for the mobile number. Uponconnecting the second communication link between the call server 102 andthe called communication device 410, the call server 102 joins the firstcommunication link with the second communication link to create afull-duplex communications session (e.g., media channel connection)between the hybrid mobile device 124 and the called communication device410.

To receive a call into the hybrid mobile device 124, the othercommunication device 410 dials the hybrid mobile device's data telephonenumber. The call server 102 will receive the call as the data telephonenumber dialed by communication device 410 is associated with the callserver 102. Call server 102 establishes a first communication link withthe communication device 410 and then determines the status of thehybrid mobile device 124 associated with the data telephone number.

If the hybrid mobile device 124 is currently connected to an IP accesspoint 120 (e.g., a WiFi connection), the call server 102 will establisha second communication link with the hybrid mobile device 124 over theIP network 101/122. Upon connecting the second communication linkbetween the call server 102 and the hybrid mobile device 124, the callserver 102 joins the first communication link with the secondcommunication link to create a full-duplex communications session (e.g.,media channel connection) between the hybrid mobile device 124 and thecalled communication device 410.

If the hybrid mobile device 124 is not currently connected to an IPaccess point 120 (e.g., a WiFi connection), the call server 102 willestablish a second communication link with the hybrid mobile device 124over the mobile carrier network 110. This may be done by looking up thedata telephone number in a database and retrieving an associated mobilenumber for the hybrid mobile device 124. The call server then calls themobile number to establish the second communication link. Uponconnecting the second communication link between the call server 102 andthe hybrid mobile device 124, the call server 102 joins the firstcommunication link with the second communication link to create afull-duplex communications session (e.g., media channel connection)between the hybrid mobile device 124 and the called communication device410.

In all of the aforementioned call establishment scenarios, the calledcommunication device 410 may be a mobile device 114, a POTS phone 116,or a VoIP phone 118. The communication link between the call server 102and the called communication device 410 may be routed over theappropriate network depending on the type of communication device 410.

FIG. 5 is a block diagram illustrating a communication session handoffbetween a hybrid mobile device 124 and a call server 102 utilizingdifferent networks 510, 520 according to one or more embodimentsdescribed herein. Once a call has been established between a hybridmobile device 124 and another communication device 410 with the callserver 102 acting as a bridge connecting the two communication devicesas described above, the communication session will stay active until oneof the respective communication devices terminates the call.

Sometimes, however, the hybrid mobile device 124 may experience a lossof service with or degradation to the original network 510 connectionused to establish the call. The original network 510 may be a mobilecarrier network 110 or an IP network 122/101. In such a scenario, it isnecessary to hand the call over (e.g., handoff) to an alternate network520 to avoid terminating the communication session. The alternatenetwork 520 may be the opposite of the original network 510. Forexample, if the original network 510 was an IP network 122/101, thealternate network 520 maybe a mobile carrier network 110 and vice versa.The embodiments are not limited to these examples. There may be otheralternate network(s) 520 that are neither mobile carrier network(s) 110or IP network(s) 122/101. The embodiments described herein apply so longas the original network and the alternate network are not the same.

The handoff may be accomplished by creating an alternate communicationlink between the call server 102 and the hybrid mobile device 124. Thealternate communication link, however, will be routed through thealternate network 520 to the hybrid mobile device 124. When the originalcommunication link is lost or is significantly degraded, it may beseamlessly replaced by the alternate communication link such that thecall server 102 bridges or connects the alternate communication linkwith the communication link to the other communication device 410 tomaintain the communication session.

To establish the alternate communication link, the hybrid mobile device124 may initially send an out of band or even an out of network signalto the call server 102. A call between the hybrid mobile device 124 anda called communication device 410 by way of call server 102 may be setupusing the session initiation protocol (SIP). IP addresses and ports areexchanged and an audio (and/or video) codec is negotiated for theexchange of media. Audio (and/or video) from both ends flows using RTPand the selected codec(s). An further change in the call is accomplishedusing SIP (e.g., one party hangs up). The hybrid mobile device 124 mayalso maintain an open data channel with the call server 102 using, forexample, a protocol called Message Queue Telemetry Transport (MQTT).MQTT is an open message protocol for machine-to-machine communicationsthat enables the transfer of telemetry-style data in the form ofmessages from pervasive devices, along high latency or constrainednetworks, to a server or small message broker. Pervasive devices mayrange from, for example, sensors and actuators, to mobile phones,embedded systems on vehicles, or laptops and full-scale computers.

The MQTT channel is not involved in the initial call setup. As long asthe communication device has some sort of network connection, the MQTTchannel is available. The impending handoff signal may be sent from thecommunication device to the server using this data channel. The MQTTchannel is out of band in the sense that it is not involved with theinitiation or destruction of a communication session (e.g., phone call).Nor is it in the path of the exchange of media between the hybrid mobiledevice 124 and the call server 102. Additionally or alternatively, theimpending handoff signal could be out of band in the sense that it usesan alternate network type. For example, a text message, white space, orLTE. This may be referred to herein as an out of network signal.

The out of band or out of network signal may instruct the call server102 to initiate the process of establishing an alternate communicationlink between the hybrid mobile device 124 and the call server 102. Theout of band or out of network signal may be the result of the hybridmobile device 124 detecting poor or degrading original networkconnectivity or may be based on one or more other sensor inputsindicative of the impending need for a handoff. Once the out of band orout of network signal requesting establishment of an alternatecommunication link is received, the call server 102 may initiate thealternate communication link by first determining on what network theoriginal communication link is established. The call server 102 may thendial the hybrid mobile device 124 using the telephone number associatedwith the alternate network connection 520 to the hybrid mobile device124. The hybrid mobile device 124 may then automatically answer the callwithout user notification or intervention. The call server 102 may thenjoin the alternate communication link with communication link to theother communication device 410 to maintain the communication sessionbefore severing the original communication link between hybrid mobiledevice 124 and the call server 102.

For example, if the original network connection 510 for the originalcommunication link is a VoIP based WiFi connection, the alternatecommunication link may be established over a mobile carrier network viaa cellular system. The hybrid mobile device 124 will have both a datatelephone number associated with, in this example, the original network510 and a mobile telephone number associated with the alternate network520. The alternate communication link may be routed over the alternatenetwork 520 by having the call server 102 send call establishmentsignaling to the hybrid mobile device 124. Since the hybrid mobiledevice 124 is currently connected to the call server on the originalcommunication link, the incoming new call signaling may be acted uponwithout notifying the user. For instance, the hybrid mobile device 124may not ring, vibrate, or display a call waiting message pertaining tothe incoming call from the call server 102. Rather, the hybrid mobiledevice 124 may automatically answer the new incoming call over thealternate network 520 based on a particular piece of information in thesignaling data that identifies the new call as being a handoff for thecurrent call. For example, the out of band or out of network signal sentby the hybrid mobile device 124 to the call server 102 may include aflag or data bits uniquely signifying a request to create an alternatecommunication link between the hybrid mobile device 124 and the callserver 102 and switch from the original communication link to thealternate communication link. In another embodiment, the call server mayuse a particular telephone number as the source number when signalingthe hybrid mobile device 124. The particular number may be dedicated tohandoff calls only.

The technique(s) described may work whether the original network 510 isan IP based VoIP network 122/101 and the alternate network 520 is acellular based mobile carrier network 110 or vice versa. In addition,there may be other types of non-cellular based network(s) that canfunction as the original network 510 or alternate network 520. Theembodiments are not limited to these examples.

Included herein is a set of flow charts and message diagramsrepresentative of exemplary methodologies for performing novel aspectsof the disclosed architecture. While, for purposes of simplicity ofexplanation, the one or more methodologies shown herein, for example, inthe form of a flow chart or flow diagram, are shown and described as aseries of acts, it is to be understood and appreciated that themethodologies are not limited by the order of acts, as some acts may, inaccordance therewith, occur in a different order and/or concurrentlywith other acts from that shown and described herein. For example, thoseskilled in the art will understand and appreciate that a methodologycould alternatively be represented as a series of interrelated states orevents, such as in a state diagram. Moreover, not all acts illustratedin a methodology may be required for a novel implementation.

FIG. 6 illustrates one embodiment of a logic flow 600 for executing ahandoff of a portion of a communication session between differentnetworks. The logic flow 600 may be representative of some or all of theoperations executed by one or more embodiments described herein. In thisembodiment, steps are disclosed that allow a hybrid mobile device 124 tosignal a call server 102 that a handoff from an original communicationlink to an alternate communication link is needed.

In the illustrated embodiment shown in FIG. 6, the logic flow 600 maydetermine that a handoff is needed between the hybrid mobile device 124and the call server 102 at block 605. For example, it is presumed that acommunication session as described earlier has been established. Thehybrid mobile device 124 may detect that the current network connectionfor the hybrid mobile device 124 is degrading and in danger of completeloss or an unacceptable level of quality. One indicator may include aweakening signal strength between the hybrid mobile device 124 and anetwork access point to which the mobile hybrid device 124 is connected.The network access point could be IP based 120 in the case of a VoIPWiFi connection or a basestation 112 in the case of a cellularconnection to a mobile carrier network 110.

The logic flow 600 may send an out of band or out of network signal fromthe hybrid mobile device 124 to the call server 102 at block 610. Forexample, the hybrid mobile device 124 upon determining a handoff betweennetworks may be needed may create an out of band signal to be sent tothe call server 102. The out of band signal may comprise a signal sentover an MQTT data channel and may also include a data indicating ahandoff from the current network connection to an alternate networkconnection is needed. In another embodiment, the out of band signal maybe replaced with an out of network signal. An out of network signal maycomprise a signal that is sent over a network that is not the networkcurrently being used by the hybrid mobile device 124 for thecommunication session. The out of network signal may be out of networkin the sense that it uses an alternate network type such as, forexample, a text message, white space, or LTE.

The logic flow 600 may initiate a new call to the hybrid mobile device124 at block 615. For example, the call server 102 may signal the hybridmobile device 124 over the alternate network 520 to establish a newcommunication link. If the alternate network 520 is a mobile carriernetwork 110, for example, the call server 102 may place a call to atelephone number associated with both the hybrid mobile device 124 andthe mobile carrier network 110. If the alternate network 520 is a IPdata network 122/101 using VoIP telephony protocols, for example, thecall server 102 may place a call to a telephone number associated withboth the hybrid mobile device 124 and the IP data network 122/101 usingVoIP telephony protocols.

The logic flow 600 may receive a new call but suppress user notificationat block 620. For example, the hybrid mobile device 124 may receive thenew call made to it by the call server 102 at step 615. Upon receipt ofthe new call, the hybrid mobile device 124 may recognize the source ofthe call as being the call server 102 and also determine that theincoming new call is occurring shortly after the hybrid mobile device124 sent the out of band or out of network signal indicating that ahandoff may be needed. Knowing that information, the hybrid mobiledevice 124 may suppress the typical incoming call user notificationssuch as ringing, vibrating, etc. and automatically answer the call atblock 625.

The logic flow 600 may sever the original network 510 connection atblock 630. For example, the hybrid mobile device 124 and/or the callserver 102 may sever the original communication link between the hybridmobile device 124 and the call server 102 on the original network 510immediately after establishing the new communication link on thealternate network 520. The call server 102 may then join the newcommunication link on the alternate network with the communication linkbetween the other communication device 410 and the call server 102 tomaintain the communication session between the hybrid mobile device 124and the other communication device 410 at block 635.

FIG. 7A is one embodiment of a messaging diagram for executing a handoffof a portion of a communication session between different networks. Inthis embodiment, a messaging diagram is described using an out of bandmessage to initiate a handoff off a communication link from an originalnetwork 510 to an alternate network 520. An original media stream 710 isshown and pre-supposes that a communication session between a hybridmobile device 124 and a second communication device 410 that isintermediated by a call server 102 exists. As described above, thehybrid mobile device 124 may have determined that a handoff from theoriginal network 510 carrying the communication link to an alternatenetwork 520 is needed based on, for example, degrading networkconditions or a weakening signal strength on the original network 510.In such a scenario, the hybrid mobile device 124 may create and send anout of band message 720 to the call server 102 indicating the need for anew communication link on an alternate network 520. The out of bandmessage 720 may comprise, for instance, a signal sent over an MQTT datachannel.

The call server 102 may receive the out of band message 720 and respondwith a call initiation 730 to the hybrid mobile device 124 over thealternate network 520. The hybrid mobile device 124 may execute a callanswer 740 process to establish a new communication link with the callserver 102 on the alternate network 520. A new media stream 750 may thenbe established between the hybrid mobile device 124 and the call server102 over the alternate network 520. The call server 102 may then severthe original media stream 760 between the hybrid mobile device 124 andthe call server 102 on the original network 510. The call server 102 maythen join the new communication link to the communication sessionreplacing the original communication link such that communicationsession between the hybrid mobile device 124 and the other communicationdevice 410 is maintained.

FIG. 7B is another embodiment of a messaging diagram for executing ahandoff of a portion of a communication session between differentnetworks. In this embodiment, a messaging diagram is described using anout of network message to initiate a handoff off a communication linkfrom an original network 510 to an alternate network 520. An originalmedia stream 710 is shown and pre-supposes that a communication sessionbetween a hybrid mobile device 124 and a second communication device 410that is intermediated by a call server 102 exists. As described above,the hybrid mobile device 124 may have determined that a handoff from theoriginal network 510 carrying the communication link to an alternatenetwork 520 is needed based on, for example, degrading networkconditions or a weakening signal strength on the original network 510.In such a scenario, the hybrid mobile device 124 may create and send anout of network message 725 to the call server 102 indicating the needfor a new communication link on an alternate network 520. The out ofnetwork message 725 may comprise, for example, a signal sent over analternate network 520 such as, for instance, a text message network, awhite space network, or an LTE network.

The call server 102 may receive the out of network message 725 andrespond with a call initiation 730 to the hybrid mobile device 124 overthe alternate network 520. The hybrid mobile device 124 may execute acall answer 740 process to establish a new communication link with thecall server 102 on the alternate network 520. A new media stream 750 maythen be established between the hybrid mobile device 124 and the callserver 102 over the alternate network 520. The call server 102 may thensever the original media stream 760 between the hybrid mobile device 124and the call server 102 on the original network 510. The call server 102may then join the new communication link to the communication sessionreplacing the original communication link such that communicationsession between the hybrid mobile device 124 and the other communicationdevice 410 is maintained.

Some embodiments may be described using the expression “one embodiment”or “an embodiment” along with their derivatives. These terms mean that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment. Theappearances of the phrase “in one embodiment” in various places in thespecification are not necessarily all referring to the same embodiment.Further, some embodiments may be described using the expression“coupled” and “connected” along with their derivatives. These terms arenot necessarily intended as synonyms for each other. For example, someembodiments may be described using the terms “connected” and/or“coupled” to indicate that two or more elements are in direct physicalor electrical contact with each other. The term “coupled,” however, mayalso mean that two or more elements are not in direct contact with eachother, but yet still co-operate or interact with each other.

Although the flowcharts and message diagrams of FIGS. 6-7B each show aspecific order of execution, it is understood that the order ofexecution may differ from that which is depicted. Also, steps shown insuccession in the flowcharts may be executed concurrently or withpartial concurrence. Further, in some embodiments, one or more of thesteps shown in the flowcharts may be skipped or omitted. In addition,any number of counters, state variables, warning semaphores, or messagesmight be added to the logical flows described herein, for purposes ofenhanced utility, accounting, performance measurement, or providingtroubleshooting aids, etc. It is understood that all such variations arewithin the scope of the present disclosure.

Where any component discussed herein is implemented in the form ofsoftware, any one of a number of programming languages may be employedsuch as, for example, C, C++, C#, Objective C, Java, Javascript, Perl,PHP, Visual Basic, Python, Ruby, Delphi, Flash, or other programminglanguages. Software components are stored in a memory and are executableby a processor. In this respect, the term “executable” means a programfile that is in a form that can ultimately be run by a processor.Examples of executable programs may be, for example, a compiled programthat can be translated into machine code in a format that can be loadedinto a random access portion of a memory and run by a processor, sourcecode that may be expressed in proper format such as object code that iscapable of being loaded into a random access portion of a memory andexecuted by a processor, or source code that may be interpreted byanother executable program to generate instructions in a random accessportion of a memory to be executed by a processor, etc. An executableprogram may be stored in any portion or component of a memory including,for example, random access memory (RAM), read-only memory (ROM), harddrive, solid- state drive, USB flash drive, memory card, optical discsuch as compact disc (CD) or digital versatile disc (DVD), floppy disk,magnetic tape, or other memory components.

A memory is defined herein as including both volatile and nonvolatilememory and data storage components. Volatile components are those thatdo not retain data values upon loss of power. Nonvolatile components arethose that retain data upon a loss of power. Thus, a memory maycomprise, for example, random access memory (RAM), read-only memory(ROM), hard disk drives, solid-state drives, USB flash drives, memorycards accessed via a memory card reader, floppy disks accessed via anassociated floppy disk drive, optical discs accessed via an optical discdrive, magnetic tapes accessed via an appropriate tape drive, and/orother memory components, or a combination of any two or more of thesememory components. In addition, the RAM may comprise, for example,static random access memory (SRAM), dynamic random access memory (DRAM),or magnetic random access memory (MRAM) and other such devices. The ROMmay comprise, for example, a programmable read-only memory (PROM), anerasable programmable read-only memory (EPROM), an electrically erasableprogrammable read-only memory (EEPROM), or other like memory device.

The devices described herein may include multiple processors andmultiple memories that operate in parallel processing circuits,respectively. In such a case, a local interface, such as a communicationbus, may facilitate communication between any two of the multipleprocessors, between any processor and any of the memories, or betweenany two of the memories, etc. A local interface may comprise additionalsystems designed to coordinate this communication, including, forexample, performing load balancing. A processor may be of electrical orof some other available construction.

Although the bridge/routing module 102 a, intelligence module 102 b, andhandoff module 102 c and other various systems and components describedherein may be embodied in software or code executed by general purposehardware, as an alternative the same may also be embodied in dedicatedhardware or a combination of software/general purpose hardware anddedicated hardware. If embodied in dedicated hardware, each can beimplemented as a circuit or state machine that employs any one of or acombination of a number of technologies. These technologies may include,but are not limited to, discrete logic circuits having logic gates forimplementing various logic functions upon an application of one or moredata signals, application specific integrated circuits havingappropriate logic gates, or other components, etc. Such technologies aregenerally well known by those skilled in the art and, consequently, arenot described in detail herein.

Also, any logic, functionality or application described herein,including the bridge/routing module 102 a, intelligence module 102 b,and handoff module 102 c, that comprises software or code can beembodied in any non-transitory computer-readable medium for use by or inconnection with an instruction execution system such as, for example, aprocessor in a computer system or other system. In this sense, the logicmay comprise, for example, statements including instructions anddeclarations that can be fetched from the computer-readable medium andexecuted by the instruction execution system. In the context of thepresent disclosure, a “computer-readable medium” can be any medium thatcan contain, store, or maintain the logic or application describedherein for use by or in connection with the instruction executionsystem. The computer-readable medium can comprise any one of manyphysical media such as, for example, magnetic, optical, or semiconductormedia. More specific examples of a suitable computer-readable mediumwould include, but are not limited to, magnetic tapes, magnetic floppydiskettes, magnetic hard drives, memory cards, solid-state drives, USBflash drives, or optical discs. Also, the computer- readable medium maybe a random access memory (RAM) including, for example, static randomaccess memory (SRAM) and dynamic random access memory (DRAM), ormagnetic random access memory (MRAM). In addition, the computer-readablemedium may be a read-only memory (ROM), a programmable read-only memory(PROM), an erasable programmable read-only memory (EPROM), anelectrically erasable programmable read-only memory (EEPROM), or othertype of memory device.

What has been described above includes examples of the disclosedarchitecture. It is, of course, not possible to describe everyconceivable combination of components and/or methodologies, but one ofordinary skill in the art may recognize that many further combinationsand permutations are possible. Accordingly, the novel architecture isintended to embrace all such alterations, modifications and variationsthat fall within the spirit and scope of the appended claims.

1. A method comprising: hosting a communication session in a call serverbetween a first communication device and a second communication device,the call server operable in an Internet Protocol (IP) based packet datanetwork in which: (i) the call server functions as a bridge servicebetween the first communication device and the second communicationdevice joining an original communication link between the firstcommunication device and the call server with a second communicationlink between the second communication device and the call server tocreate a communication session between the first and secondcommunication devices, and (ii) the first communication device includesat least two RF transceivers each capable of communicating with the callserver over a separate network, wherein the original communication linkbetween the first communication device and the call server is initiallyestablished over an original network; receiving, in the call server, anout of band signal from the first communication device, the out of bandsignal indicative of the need to handoff the original communication linkto an alternate communication link between the first communicationdevice and the call server on an alternate network; establishing thealternate communication link between the first communication device andthe call server on the alternate network; and joining the alternatecommunication link between the first communication device and the callserver on the alternate network with the second communication linkbetween the second communication device and the call server to maintainthe communication session between the first and second communicationdevices.
 2. The method of claim 1, wherein the out of band signal issent over a Message Queue Telemetry Transport (MQTT) data channel. 3.The method of claim 1, wherein the original network is one of a VoIP IPdata network, a mobile carrier network, a WiMax network, and awhitespace network.
 4. The method of claim 1, wherein the alternatenetwork is one of a VoIP IP data network, a mobile carrier network, aWiMax network, and a whitespace network.
 5. The method of claim 1,further comprising severing the original communication link between thefirst communication device and the call server.
 6. A method comprising:hosting a communication session in a call server between a firstcommunication device and a second communication device, the call serveroperable in an Internet Protocol (IP) based packet data network inwhich: (i) the call server functions as a bridge service between thefirst communication device and the second communication device joiningan original communication link between the first communication deviceand the call server with a second communication link between the secondcommunication device and the call server to create a communicationsession between the first and second communication devices, and (ii) thefirst communication device includes at least two RF transceivers eachcapable of communicating with the call server over a separate network,wherein the original communication link between the first communicationdevice and the call server is initially established over an originalnetwork; receiving, in the call server, an out of network signal over anetwork that is not the original network from the first communicationdevice, the out of network signal indicative of the need to handoff theoriginal communication link to an alternate communication link betweenthe first communication device and the call server on the alternatenetwork; establishing the alternate communication link between the firstcommunication device and the call server on the alternate network; andjoining the alternate communication link between the first communicationdevice and the call server on the alternate network with the secondcommunication link between the second communication device and the callserver to maintain the communication session between the first andsecond communication devices.
 7. The method of claim 6, wherein theoriginal network is one of a VoIP IP data network, a mobile carriernetwork, a WiMax network, and a whitespace network.
 8. The method ofclaim 6, wherein the alternate network is one of a VoIP IP data network,a mobile carrier network, a WiMax network, and a whitespace network. 9.The method of claim 6, further comprising severing the originalcommunication link between the first communication device and the callserver.
 10. A call server operable in an Internet Protocol (IP) basedpacket data network, the call server comprising: a processor operable toexecute one or more software modules, the software modules includinginstructions that when executed: host a communication session between afirst communication device and a second communication device wherein:(i) the call server functions as a bridge service between the firstcommunication device and the second communication device joining anoriginal communication link between the first communication device andthe call server with a second communication link between the secondcommunication device and the call server to create a communicationsession between the first and second communication devices, and (ii) thefirst communication device includes at least two RF transceivers eachcapable of communicating with the call server over a separate network,wherein the original communication link between the first communicationdevice and the call server is initially established over an originalnetwork; receive an out of band signal from the first communicationdevice, the out of band signal indicative of the need to handoff theoriginal communication link to an alternate communication link betweenthe first communication device and the call server on an alternatenetwork; establish the alternate communication link between the firstcommunication device and the call server on the alternate network; andjoin the alternate communication link between the first communicationdevice and the call server on the alternate network with the secondcommunication link between the second communication device and the callserver to maintain the communication session between the first andsecond communication devices.
 11. The call server of claim 10, whereinthe out of band signal is sent over a Message Queue Telemetry Transport(MQTT) data channel.
 12. The call server of claim 10, wherein theoriginal network is one of a VoIP IP data network, a mobile carriernetwork, a WiMax network, and a whitespace network.
 13. The call serverof claim 10, wherein the alternate network is one of a VoIP IP datanetwork, a mobile carrier network, a WiMax network, and a whitespacenetwork.
 14. The call server of claim 10, further comprising severingthe original communication link between the first communication deviceand the call server.
 15. A call server operable in an Internet Protocol(IP) based packet data network, the call server comprising: a processoroperable to execute one or more software modules, the software modulesincluding instructions that when executed: host a communication sessionbetween a first communication device and a second communication devicewherein: (i) the call server functions as a bridge service between thefirst communication device and the second communication device joiningan original communication link between the first communication deviceand the call server with a second communication link between the secondcommunication device and the call server to create a communicationsession between the first and second communication devices, and (ii) thefirst communication device includes at least two RF transceivers eachcapable of communicating with the call server over a separate network,wherein the original communication link between the first communicationdevice and the call server is initially established over an originalnetwork; receive an out of network signal over a network that is not theoriginal network from the first communication device, the out of networksignal indicative of the need to handoff the original communication linkto an alternate communication link between the first communicationdevice and the call server on the alternate network; establish thealternate communication link between the first communication device andthe call server on the alternate network; and join the alternatecommunication link between the first communication device and the callserver on the alternate network with the second communication linkbetween the second communication device and the call server to maintainthe communication session between the first and second communicationdevices.
 16. The call server of claim 15, wherein the original networkis one of a VoIP IP data network, a mobile carrier network, a WiMaxnetwork, and a whitespace network.
 17. The call server of claim 15,wherein the alternate network is one of a VoIP IP data network, a mobilecarrier network, a WiMax network, and a whitespace network.
 18. The callserver of claim 15, further comprising severing the originalcommunication link between the first communication device and the callserver.